Abstract:

This study selected Quercus mongolica, Fraxinus mandshurica, Phellodendron amurense, Juglans mandshurica, Tilia amurensis and Pinus koraiensis trees with same age (12 years old) and seedling origin under the same site conditions, and simultaneously measured the sapflow density, water consumption, and related environmental factors using thermal dissipation method and ICT-2000TE(Transpiration Environment)automatic measuring system for tree transpiration and environmental factors. In clear days during the growing season, the sapflow density exhibited mono peak diurnal patterns, mostly peaked between 10:00 to 14:00 except for P.amurense, of which the sapflow showed two peaks during daytime for three times. The PAR (photosynthetically active radiation) and VPD(vapour pressure deficit)were the major factors influencing diurnal changes in sapflow, which explained 60%～74% variations in sapflow density for all tree species except P.amurense. Maximum sapflow densities for F.mandshurica, P.amurense, Q.mongolica, J.mandshurica, T.amurensis, and P.koraiensis were 516 36, 234 00, 625 93, 945 83, 507 93, 286 21 cm 3·cm^-2 h^-1 , occurring in July, June, September, August, August, and July, respectively. Water consumption in the whole growing season for J.mandshurica, T.amurensis, F.mandshurica, P.koraiensis, P.amurense, and Q.mongolica were 3 840, 2 820, 2 710, 2 120, 1 470, and 1 390 kg·sapling^-1 , respectively.

Key words: major tree species in northeast China, sapflow, water consumption, temporal dynamics